tree 3afb6dba67015026cd713edd4d5fbea02a073fd3
parent 0ea9b91e0f78ffcb88c903e665a39d61afc710af
author Harald Welte <laforge@osmocom.org> 1685451698 +0200
committer laforge <laforge@osmocom.org> 1685694595 +0000

libosmogsm: Allow auth API caller to specify RES length

There are 3G algorithms which support different lengths of RES values
(4, 8, 16 byte).  For MILENAGE, we never really had to bother, as
the 4-byte RES is simply the first 4 bytes of the 8-byte RES.

However, for TUAK, the expected RES length is an input parameter to
the Keccak crypto functions, so the result of all parameters (including
CK, IK, ...) will be completely different for RES length 4 than RES
length 8.

So let's permit the caller of the osmocom auth API to specify the
requested RES length via the osmo_auth_vector.res_len parameter.

For backwards compatibility of callers of the old osmo_auth_gen_vec/
osmo_auth_gen_vec_auts API: Always force the res_len to 8 in this case,
which was the hard-coded length before this patch.

Change-Id: Ic662843fbe8b5c58e4af39ea630ad5ac13fd6bef